Method for effluent treatment in smelting of nickel oxide ore

Abstract

The present invention aims at providing a method for effluent treatment, which enables the separation and recovery of a high-density and high-concentration aluminum sediment from waste water that is discharged in the smelting of a nickel oxide ore and contains aluminum ions. In the present invention, an alkali and an iron-containing solid are added to waste water containing aluminum ions to form a slurry, and the slurry is allowed to stand to perform solid-liquid separation, whereby an aluminum sediment and an effluent is formed.

The invention claimed is: 
     
       1. A method for treatment of waste water that is discharged in the smelting of a nickel oxide ore, comprising:
 adding an alkali and an iron-containing solid to the waste water containing aluminum ions to form a slurry; and 
 allowing the slurry to stand to perform solid-liquid separation to form an aluminum sediment and an effluent; 
 wherein the iron-containing solid is a leached residue obtained by subjecting the nickel oxide ore to high pressure leach with addition of sulfuric acid. 
 
     
     
       2. The method for treatment of an effluent in the smelting of a nickel oxide ore according to  claim 1 , wherein adding an alkali and an iron-containing solid to the waste water containing aluminum ions to form a slurry comprises:
 adding the alkali to the waste water to form a slurry, and then 
 adding the iron-containing solid to the slurry. 
 
     
     
       3. The method for treatment of an effluent in the smelting of a nickel oxide ore according to  claim 1 , wherein the alkali is added to the waste water in an amount to adjust the pH of the waste water to 4.0 or more. 
     
     
       4. The method for treatment of an effluent in the smelting of a nickel oxide ore according to  claim 1 , wherein the iron-containing solid is added in an amount that corresponds to 50% by weight or more and 200% by weight or less with respect to an amount of an aluminum sediment that generates in the case when the solid is not added. 
     
     
       5. The method for treatment of an effluent in the smelting of a nickel oxide ore according to  claim 4 , wherein the iron-containing solid is added in an amount so that the slurry has a specific gravity in a range of 1.1 g/ml or more and 1.4 g/ml or less.